Influence of genetic variables on means, variances, and covariances in behavioral responses to toxicological and pharmacological substances.

Inbred strains and F1 generations provide strong experimental control in toxicological studies by virtue of the relative stability of their means. Their variances do not always conform to simple expectations, with respect either to each other or to segregating populations. For the evaluation of covariances or correlations, populations of choice are genetically segregating ones. A genetic approach of demonstrated power but as yet limited application to toxicological problems is that of selective breeding, a procedure by which lines of animals can be developed to precise specifications.